1 GIT repository which contains client/server/shared code, currently on 1 branch.
Typically you would like to separate your Source Control, build process and deployable artifacts. Git is primarily for Source Control, the accepted practice is to only have source code in it.
Then you would have it built with some build tool (Jenkins, bamboo etc.) Then you can either use the build result from the build tool, or if you prefer use a version control for your artifacts like Nexus or artifactory.
This may sound complicated, but does avoid a lot of problems in future.